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From tsuraan <>
Subject Re: Re: Modelling assets and user permissions
Date Tue, 20 Apr 2010 17:37:57 GMT
> I'm curious as to how you would have so many asset / user permissions that
> you couldn't use a standard relational database to model them. Is this some
> sort of multi-tenant system where you're providing some generalized asset
> check-out mechanism to many, many customers? Even so, I'm not sure the
> eventually consistent model wouldn't open you up to check-out collisions, as
> you mention yourself.

The assets are binary files on a document tracking system.  Our
current platform is postgres-backed; the entire system we've written
is fairly easily distributed across multiple computers, but postgres
isn't.  There are reliable databases that do scale out, but they tend
to be a little on the pricey side...  Our current system works well in
the tens to hundreds of millions of documents with hundreds of users,
but we're hitting the billions of documents with thousands of users,
so cassandra's scaling properties are pretty appealing there.

I don't think eventual consistency would be a terrible problem; so
long as our system lives in a rack, or at least in a single data
center I think the database would become consistent before the
documents would be visible by any users of the system.

> Am I missing something about your example?

Just the scale, I think.  I like relational databases, but I'm really
interested in trying out cassandra's way, if I can come up with a sane
way to model my system in it.

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